Foldable beds, and particularly those folding beds which are stored within other furniture items, are an attractive bedding option for consumers with restricted living space. Typically a foldable bed folds upon itself either one or two times for easy storage, then unfolds into a bed for sleeping. The bed generally includes a mattress that is sufficiently flexible to fold upon itself and a frame which serves as both the supporting bed frame and a restraining unit for the mattress in its folded position. The typical frame includes a body section pivotally attached at one end to the end of an intermediate cavity section, the opposite end of which is attached to a seat section; these sections are serially aligned horizontally in the unfolded position, and are folded back upon one another such that the body section and seat section are substantially parallel to one another and are perpendicular to the cavity section in the folded position. The frame is often mounted in an upholstered sofa or chair frame into which the bed frame and mattress are folded and stored when not in use. Cushions are then placed upon the folded mattress for use of the unit as a sofa or chair.
To date, foldable beds have exhibited a number of shortcomings. One general area of dissatisfaction is the sleeping comfort of the bed. For storage purposes, it is desirable that the mattress fold into the thinnest package possible. The need for a compactly folded mattress is particularly important if the mattress and frame are attached to a sofa or chair, since the mattress and frame must fit within the walls of the sofa or chair, which likely has style or ergonomic restrictions. Thick, firm mattresses that would provide suitable sleeping comfort are too bulky to be folded into the space available in many sofa or chair styles; in particular, transitional and contemporary styles often have either a low seat height or an "off-the-floor" front profile and thereby have limited space available in which to store a bed. Many present sofas have addressed the size constraint by employing a mattress that is either (a) thin and easily folded into a thin unit, (b) soft and easily crushed, or (c) a combination of each. The result of such compromises is often an unsatisfactory sleeping surface.
Attempts have been made to address the aforementioned problem. One solution has been the development of so-called "collapsible" springs that comprise some or all of the supporting springs in the mattress. These springs are generally planar and are pivotally interconnected at each end to a pair of wire grids that are adjacent and parallel with the upper and lower upholstery faces of the mattress. When the bed is in its unfolded position, the springs are upright and are oriented to be parallel with the head and foot end faces of the mattress and orthogonal to the upper, lower, and lateral faces of the mattress. However, as the bed moves to its folded position, the springs pivot relative to the wires comprising the grids so that the mattress upper surface is drawn closer and shifts longitudinally relative to the mattress lower surface. As a result, the distance between the upper and lower mattress surfaces (i.e., the thickness of the mattress) is significantly decreased, thereby giving the mattress the appearance of having "collapsed". Examples of collapsible springs suitable for use in foldable bedding are illustrated in U.S. Pat. Nos. 4,489,450, 4,620,336, 4,654,905, and 5,184,809 and 5,539,944 to Miller and U.S. Pat. No. 5,257,424 to Rogers; the disclosure of these patents are hereby incorporated herein by reference in their entireties.
The use of collapsible springs can complicate the folding of the mattress. Also, because the upper and lower mattress surfaces have shifted relative to one another in the folded position, the mattress length is typically reduced in order for the mattress to fold upon itself and fit within the cavity of a conventional seating unit.
One approach, illustrated in U.S. Pat. No. 5,257,424 to Rogers, is to add an additional pivoting section to the mattress at the foot end of the seat section. This approach requires, of course, that the frame and the mechanism controlling the movement thereof have configurations that differ from those used with conventional mattresses. Another approach to this problem is described in U.S. Pat. No. 5,642,536 to Miller (the disclosure of which is hereby incorporated herein by reference in its entirety), which includes a slightly modified mattress frame that has a foot-end leg that is pivotally interconnected with the frame nearer the foot end than is conventional. As a result, in the folded position, the leg presses deeply into the head section of the mattress, thereby "clearing" additional space for the collapsed springs. Unfortunately, this approach requires the aforementioned modifications to the frame and can be deleterious to the head section of the mattress.